During replication nucleosomes are partially displaced and d

During replication, nucleosomes are partially displaced and distributed on the daughter DNA strands. New histone subunits are added to bring the entire complement of nucleosomes up to the required level. Nucleosomes on the DNA to be replicated may have modified histone subunits, but the new histones that appear after replication lack the modifications (at least transiently). Which of the following statements describes how the modified and unmodified histone subunits are distributed in nucleosomes after replication?

A)The modified and unmodified histones are assembled randomly into nucleosomes.

B)The modified histone subunits stay together in nucleosomes, separate from unmodified nucleosomes.

C)The H3-H4 modified pairs stay together, the H2A-H2B modified pairs stay together, and nucleosomes assemble with modified and unmodified H3-H4 and H2A-H2B pairs. The various combinations occur at random on each daughter DNA molecule.

D)Modified nucleosomes are segregated to one daughter chromosome, and completely unmodified nucleosomes are segregated to the other daughter chromosome.

Solution

On completion of replication of DNA, The modified histome proteins H3 and H4 bind to the daughter strands along with modified H2A and H2B proteins. These proteins are randomly arranged with unmodified histone protein pairs of H3 and H4; H2A and H2B respectively. The arrangement of histone protein pairs in different combination may take place randomly. Therefore, option C is correct.